The objective of the proposed study is to gain a better understanding of certain aspects of the regulation of synthesis and secretion of chondroitin sulfate proteoglycan at both the biochemical and cellular level. Since chondroitin sulfate proteoglycan is the end product of a complex biosynthetic pathway, a number of sites exist at which its metabolism may be regulated in the intact cell. Therefore, the various steps of biosynthesis which may serve as a locus of control will be separately assessed. (1) In cell-free studies, the composition, structure and organization of the various components, as well as the interactions of individual isolated components in selectively reassembled systems, will be examined. (2) Since modulation of glycosyltransferase activity under certain conditions of development has been demonstrated, regulation may also occur at the level of synthesis and coordination of specific glycosyltransferases. Thus, protein-synthesizing elements involved in formation of glycosyltransferases will be isolated and identified. (3) In a cell culture system, about which much information concerning the biochemical and enzymatic parameters of chondroitin sulfate proteoglycan synthesis is known, certain aspects of the intracellular mechanisms, subcellular localization and energy requirements involved in secretion of chondroitin sulfate proteoglycan and free chondroitin sulfate chains will be determined. (4) The chondrocyte tissue culture system also provides an opportunity to investigate whether collagen synthesis and/or secretion can be altered by controlling an aspect of chondroitin sulfate synthesis which eventually may reveal if the biosynthetic processes of these two matrix macromolecules are metabolically interrelated.